We know sex is good for us. Now scientists say it can also protect against
disease, writes Lucy Atkins.

IT DOES not take a degree in medicine to work out that sex is good for
you. Anything that is free, feels fabulous and leaves you glowing is plainly
a good idea.

But scientists are now beginning to understand that the perceived feel-good
effects of sexual intercourse are merely the tip of the iceberg. Sex, they
are discovering, can offer protection from depression, colds, heart disease
and even cancer.

The latest addition to the body of evidence came last month when Professor
Stuart Brody of the University of Paisley published a study showing sex
can lower blood pressure.

"We're not just talking about the immediate effects of having had nice
sex. The beneficial effects could last at least a week," says Professor
Brody.

One theory is that intercourse stimulates a variety of nerves, most
notably the "vagas" nerve, which is directly involved in soothing and calming.
But you have to go the whole heterosexual hog. According to Professor Brody,
studies show "penile-vaginal intercourse is the only sexual behaviour consistently
associated with better psychological and physiological health".

Such sex has been linked, in women, to a heightened emotional awareness,
possibly because the "love hormone" oxytocin is released. One study even
found that semen is a mood-enhancing ingredient.

Doctors speculate that this is because semen contains several other
mood-altering hormones — including testosterone, oestrogen, prolactin and
several different prostaglandins — which can pass into the woman's bloodstream.
This explanation, says Dr David Hicks, sexology specialist and consultant
in GU medicine at the Royal Hallamshire Hospital in Sheffield, "is certainly
feasible". Condom-free sex has its drawbacks, of course: contracting a
sexually transmitted disease or becoming pregnant unintentionally.

If you are dogged by the sniffles at this time of year, regular love-ins
could work wonders for your immunity — condoms and all. Psychologists have
found that people who have sex once or twice a week have levels of immunoglobulin
A (IgA) that are up to a third higher than their more restrained peers.
IgA is an antibody that boosts the immune system and is the first line
of defence against colds and flu.

The health benefits for middle-aged men are also particularly persuasive.
Recent studies suggest that men who have orgasms twice a week are half
as likely to die early as men who orgasm less than once a month.

The more frequently men ejaculate, the less likely they are to develop
prostate cancer, and if middle-aged men have sex twice a week or more they
also have a lower risk of heart attack. Much has been made of the slimming
and toning effects of a sexual work-out. In fact, sex probably burns off
about the same number of calories per minute as a brisk walk. "You get
all the benefits of exercise," confirms Dr Hicks. "This includes the release
of endorphins, raised heart rate, moving the muscles and joints."

You might also look younger. "Regular sex makes you feel younger as
you are more relaxed, satisfied and less stressed," says Dr Kevan Wylie,
consultant andrologist at the Royal Hallamshire Hospital.

"Sex has huge mental benefits," adds Dr Hicks. "It's the outward proof
that you are wanted, desired and valued." And if you feel sexy, you tend
to look it, too.

Sex is not, sadly, a cure-all. "There is a danger in thinking that we
can fix anything by leaping into bed," says Dr Petra Boynton, a psychologist
at University College in London specialising in sex and relationships.
"The fact is you are likely to have a much better sex life if you are healthy
and happy, rather than the other way round." Still, it can't hurt to try.